Authors
Abstract
The synthesis of mullite from an aluminous-rich mine waste (shale) closely associated with iron/manganese mines from Bonai-Keonjhar belt, Odisha is reported. The shale constitutes major kaolinite with minor halloysite, quartz, orthoclase and plagioclase minerals and compositionally contains 36.40 % Al2O3 and 52.10% SiO2. In order to convert this mine waste to a refractory product, ‘Mullite’, alumina powder was added in 1:0.9; 1:1 and 1:1.1 weight ratios with the shale and thoroughly homogenized. Individual mixtures were fed in to the thermal plasma reactor and processed for only 5 minutes to form mullite. The phase and microstructure developed in the processed samples were investigated from their XRD patterns, Raman spectra and SEM images. Diagnostic peaks of the mullite phase are distinctly marked in the XRD pattern and Raman spectra of plasma treated products. Microstructure of mullite observed under SEM clearly exhibits a fused layered structure. The integrated results confirm the formation of high quality mullite from a mixture of 1:1 weight ratio. This low cost process can be implemented in industrial scale for processing of such mine waste to a value added refractory product.
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